The present invention relates to data compression of decaying musical instrument sounds for a digital sampling system.
Using current digital sampling and playback techniques, it is very difficult to get significant amounts of data reduction when storing certain types of musical instrument sound data. The instruments exhibiting the most severe problems are those with wide transposition ranges and those with timbres that change over long periods of time. Typical musical instruments exhibiting these characteristics are the acoustic piano, guitars, and their relatives. Particularly difficult is the acoustic piano, owing to its wide range, long decay, and the use of multiple strings nearly in unison (hereafter "unison string") to produce a single tone.
While looping techniques for memory conservation are well known in the art, the aforementioned sounds still require large amounts of memory, even when looped. The decaying nature makes it difficult to perform a smooth, long loop, and short loops are too easily perceived. Also, loops that are placed too close to the attack portion of the note will be too harmonically rich to be interpreted as natural.